Semiconductor assemblies that include one or more dies typically require individual packaging for each die to provide the required electrical contacts or connectors that can be soldered or otherwise connected to associated printed circuit boards. The search for new connector types by the electronics industry has been driven by the need for connections having a high contact pad density, high frequency operation, decreased size, low cost, and ease of replacement.
The present invention arose from efforts to redesign single in-line memory modules (SIMM). In such modules, a plurality of integrated memory circuits are interconnected on a substrate that includes traces leading to conventional edge conductors that permit the module to be plugged into a motherboard within a computer or other specific application. Present packaging requirements for integrated circuits involve placement of a die within an individual package having external contacts. The package must be mounted securely to a printed circuit board and the integrated circuit contacts must be soldered to make interconnections to the pads and traces of the printed circuit board.
A general example of current SIMM technology is illustrated in FIG. 2. A number of packaged memory integrated circuits 27 are mounted in-line along a supporting printed circuit board 13. The integrated circuit contacts 28 are soldered to traces 29 on board 13, and lead to a row of edge conductors 14. The production of such modules not only requires assembly of the board shown in FIG. 2, but also requires packaging and assembling of the individual integrated circuits themselves. Fabrication of the SIMM requires several steps to anchor and connect the circuitry of the integrated circuits and circuit board 13. Substitution of replacement circuits 27 in a completed assembly is both difficult and time consuming.
While not limited to SIMM applications, the present invention utilizes anisotropically conductive elastomeric sheets to form multiple electrical paths between individual dies having conductive pads along one surface and an interconnecting plate having corresponding conductive pads aligned in registration with the conductive pads of the die. The die and interconnecting plate compress the interposed sheet of elastomeric material to complete the desired electrical connections. The interconnecting plate can include traces leading to conventional edge connector elements. The resulting physical module containing these dies is relatively simple in structure. It requires no prepacking of individual dies and facilitates substitution of dies within a module when this becomes necessary.
The present invention can be applied to multi-chip assemblies of one or more types of semiconductor dies. The dies can either be utilized as discrete units or in wafer form. In the context of this document the term "dies" is intended to encompass individual chips that have been singulated from an entire wafer, as well as an entire wafer of integrated circuitry. In the context of the invention, multiple dies can be assembled in high density packaging without any wire-bonding, tape automated bonding or other conventional interconnect technology applied to such dies. The invention comprises a novel construction for registering dies relative to an interconnecting plate.